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Tamoxifen Prevents Benign Breast Lesions in High-Risk Women

Tamoxifen Prevents Benign Breast Lesions in High-Risk Women

SAN ANTONIO—Tamoxifen (Nolvadex) therapy not only prevents breast
cancer but also benign breast disease in high-risk women, according to a study
by the National Surgical Adjuvant Breast and Bowel Project (NSABP) presented at
the 24th San Antonio Breast Cancer Symposium (abstract 7). Elizabeth Tan-Chiu,
MD, of the NSABP, reported the findings.

In 1998, she said, the NSABP P-I trial established that tamoxifen reduces
the incidence of invasive breast cancer (NSABP B-14), as well as ductal
carcinoma in situ and lobular carcinoma in situ (NSABP B-24) by about 50% in
women at high risk for breast cancer.

"These findings have been described as an early treatment of
subclinical invasive breast cancers rather than a true preventive effect,"
Dr. Tan-Chiu said. "It was pertinent, therefore, to look at the effect of
tamoxifen on the non-premalignant (benign) lesions of the breast." She
noted that estrogen receptors are expressed on benign as well as malignant
breast lesions.

The patient population included 13,388 women determined to be at high risk
for developing breast cancer by the Gail model. Pathology reports on all breast
biopsies performed during the study were collected prospectively. For each
histologic diagnosis, the relative risk between tamoxifen- and placebo-treated
women was evaluated. The median follow-up was 54.6 months.

Tamoxifen therapy reduced the overall incidence of benign breast disease by
28% (P < .001), the total number of women undergoing biopsies by 12%, and
the total number of biopsies by 22% (P < .001), Dr. Tan-Chiu reported.

In the NSABP P-1 trial, about 2,200 biopsies were performed. In tamoxifen
recipients, there were about 400 fewer total biopsies, and about 150 fewer
women undergoing biopsies. The effect of tamoxifen on biopsies was most evident
among women undergoing two or more biopsies vs only one, and for premenopausal
women, in whom the number of biopsies was reduced by 35%, she said.

Most, but not all, histologic types of benign lesions were affected by
tamoxifen therapy). Statistically significant relative risk
reductions (P < .001 for most) were seen in the categories of adenosis
(41%), cysts (32%), duct ectasia (29%), fibrocystic disease (33%), hyperplasia
(39%), and metaplasia (49%). Tamoxifen reduced the risk of typical hyperplasia
by 40% and atypical hyperplasia by 32%.

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